Atmospheric hazards

What is air pressure?

The weight of air above us, normal levels are 1000mb

What is happening in low pressure conditions?

Warm air is rising, it then cools, condenses and forms clouds, often leads to heavy precipitation and swirling winds

What is happening in high pressure conditions?

Air is sinking and drying, often clear blue skies with little to no wind, can be very hot or cold depending on season

What does the Coriolis effect result in for surface winds?

Deflects winds to the right in the northern hemisphere and left in the southern hemisphere 

What is the ITCZ?

Inter-tropical convergence zone

Where trade winds converge, creating wind direction of right to left (Doldrum winds)

What is happening at the equator in the 3 cell model?

The suns energy is causing warm air to rise, cool and condense forming clouds and precipitation. Air spreads to 30°N+S forming Hadley cells and low pressure is formed.

What is happening at 30°N/S in the 3 cell model?

High pressure conditions as air is sinking

What is happening at 60°N/S in the 3 cell model?

Low pressure conditions from air rising and spreading to ferrel cell or polar cell

What is happening at the poles in the 3 cell model?

High pressure conditions has air from polar cell is sinking

3 types of atmospheric winds

Easterlies, Westerlies and Trade

Different names of tropical storms

Atlantic Ocean → hurricanes

Indian Ocean → cyclones 

Pacific Ocean → typhoons 

Where are tropical storms distributed?

In the tropical zone, all travel from east west due to doldrum winds 

3 conditions needed for tropical storms to form

Water warmer than 26 degrees, deep water and trade winds

Conditions tropical storms bring as they move over an area

• Temperature and air pressure fall, causing air to rise, clouds to form, and wind to increase.

• Period of calm in the eye of the storm and gets warmer

• Rapidly falling air pressure leads to stronger winds, cumulonimbus clouds, and heavy rainfall.

• Air pressure and temperature rise, wind and rainfall subside.

How are tropical storms measured?

Saffir-Simpson scale which measures wind speed 

What are sheer winds?

Winds that move north to south and can cut off the ‘spinning top’ of storms 

Primary effects of tropical storms

Coastal habitats destroyed, businesses and agriculture damaged, drowning, injury or death, government buildings destroyed

Secondary effects of tropical storms

Flooding, rebuilding and insurance payouts, sources of income lose, economic decline, homelessness, polluted water spreading disease, food shortages, debt

Tropical storm prevention

Can’t be avoided, mitigation of climate chance could prevent higher category storms 

Tropical storm preparedness strategies

Awareness and education, evacuation plans and drills, satellite images can track areas at risk, warning system and communications in place 

Tropical storm mitigation strategies (before after and during)

Clearing loose debris before storms

Strengthen homes

Search and rescue, emergency aid

Adaptation strategies for tropical storms

Move away from high risk areas, design buildings which can withstand high winds, build flood defences such as stilts and coastal walls

Define wildfires

Extensive, uncontrolled wildfires which pose a risk to property, people and the natural environment

3 types of wildfires

• Ground - surface burns including roots, peat and grass, slow burning, minimal smoke and no flame

• Surface - leaf litter and low lying vegetation burns, low flames and some smoke

• Crown/bush - rapidly moving fire that sweeps through the upper canopy

6 conditions needed for intense wildfires

1. densely packed, flammable vegetation

2. wind to provide oxygen

3. fuel (the vegetation)

4. tinder-dry conditions from a semi-arid climate

5. recent drought

6. an ignition source (natural or human)

Global distribution of wildfires

Areas most at risk are those with dry vegetation and susceptible to lightning strikes e.g. some parts of Australia, Florida, California, Southern Europe and the Mediterranean islands

What is happening to the geographical spread of wildfires?

It’s getting wider due to climate change and positive feedback loops. Also due to rainforests now being at risk due to clearing practices getting out of hand despite the humid climate meaning they shouldn’t be

Economic effects of wildfires

Loss of crops, timber, livestock and property

Environmental effects of wildfires

Loss of wildlife, less nutrient dense soils, release of toxic gas and particulates into the atmosphere

Social effects of wildfires

Loss of property and life, increased flood risk as a secondary effect

Positive effects of wildfires

Can aid new seed germination, stimulate growth of some plants, remove insects and parasites, some plants e.g. Banksia require the heat to regenerate

Prevention of wildfires strategies

Education on how to avoid stating fires

Preparedness for wildfire strategies

Controlled clearing of litter in advance to reduce spread, increasing gap between houses and vegetation, fire-resistant materials in houses, taking out insurance, warning systems in place, community actions groups

Prediction of wildfires

Computer stimulations to comprehend and predict fire behaviour

How are wildfires dealt with as they happen?

Water and chemicals such as retardants are sprayed from the air

Flames are beaten from the ground and areas are bulldozed to reduce the spread

How are the effects of wildfires addressed?

Communities and governments try to repair damage, trees are replanted to improve the economy, reduce flood risk and improve water quality, emergency survival kits are provided, attention is directed on preparedness for the future